1. Field of the Invention
The present invention relates to cutting devices having tables and configured to be able to collect cutting chips or dust produced during a cutting operation.
2. Description of the Related Art
A cutting device having a table and known as a table circular saw has a table and a cutting unit vertically movably supported by the table via a support device disposed at a rear portion of the table. The cutting unit includes a circular rotary blade rotatably driven by a motor. An upper portion of the rotary blade is covered by a blade case. A lower portion of the rotary blade is covered by a movable cover. The movable cover is opened and closed in response to the vertical movement of the cutting unit. Thus, as the cutting unit moves downward, the movable cover is opened to gradually expose the lower portion of the rotary blade, and the exposed lower portion of the cutting blade cuts into a workpiece. As the cutting unit moves downward, the movable cover is gradually closed to cover the cutting edge of the rotary blade, for example, by a biasing force of a spring.
The rotary blade cuts into a workpiece in a direction from the upper side toward the lower side, so that a cutting operation is performed. Therefore, cutting chips produced by the cutting operation is blown upward from a cut portion. If the cutting chips are scattered around, a working environment may be degraded. In addition, if the cutting chips are deposited on the cut portion, it may be hard to see a cutting line marked on the workplace or to see the cut portion, and therefore, there is a possibility of obstructing the cutting operation. Therefore, in this kind of cutting devices, there have been proposed various devices for collecting or removing cutting chips produced around the cut portion as the cutting operation is performed.
For example, Japanese Laid-Open Patent Publication No. 2006-27104 discloses a technique of mounting a U-shaped dust guide member to a lower portion of the blade case to extend downwardly therefrom within a range that does not interfere with the workplace, so that the cutting chips produced at the cut portion are guided to a dust discharge member disposed on the upper side via the dust guide member. In this publication, a fixed-type dust guide member is disclosed as the dust guide member. A dust guide member disclosed in Japanese Laid-Open Utility Model Publication No. 3-108401 is vertically pivotally supported on the lower portion of the blade case and is configured to contact the upper surface of the workpiece for covering around the out portion with more smaller clearance therewith to further improve the collecting efficiency of the dust toward the dust discharge member.
Japanese Laid-Open Patent Publication No. 2008-73920 discloses a technique in which a dust collecting member extending downward from the blade case for guiding the cutting chips toward the dust discharge member is vertically moved in conjunction with the vertical movement of the cutting unit.
Further, according to Japanese Laid-Open Utility Model Publication No. 3-108401 noted above and EP0601805A, the dust discharge member is provided at the blade case and communicates with a dust container, so that the flow of air produced by the rotation of the rotary blade is introduced into the dust container via the dust discharge member.
Further, in this kind of cutting devices, the dust container is supported by the blade case by being connected to the dust discharge member of the blade case in communication therewith. Therefore, when the cutting unit vertically pivots, it may be susceptible that this vertical pivoting movement influences the dust container. For example, in the case that the cutting unit is positioned at its uppermost position, the transfer path between inside of the dust container and the dust discharge member may be positioned substantially horizontally.
The above known dust collecting techniques still have various problems. In the case of the dust guide member disclosed in Japanese Laid-Open. Patent Publication No. 2006-27104, because the dust guide member is fixed to the lower portion of the blade case to extend therefrom, there is a limitation in increasing its downwardly extending distance due to the necessity of avoiding interference with other parts, such as a fence for positioning the workpiece. As a result, in particular in the case of cutting a workpiece having a thin thickness, the dust guide member is brought to be positioned away from the cut portion. Therefore, it is hard to always achieve a high dust collecting efficiency.
In the case of the dust guide member disclosed in Japanese Laid-Open Utility Model Publication No. 3-108401, the dust collecting member is supported to be able to vertically pivot freely within a predetermined angular range, and therefore, the lower pivotal end is fixed. For this reason, it is hard to cope with change of the cut portion according to the change of the cutting amount of the cutting blade into the workpiece and to eventually cope with change of the blowing direction of the cutting chips.
Although the dust guide member disclosed in Japanese Laid-Open Patent Publication No. 2008-73920 is configured to vertically move in conjunction with the vertical movement of the cutting unit, its moving direction is a direction of oppositely retracting upward or a direction away from the cut portion in order to avoid interference with the workpiece. As a result, the dust collecting efficiency is low in particular in the case that the workpiece has a thin thickness.
Further, in the case of Japanese Laid-Open Utility Model Publication No. 3-108401 and EP0601805A1, the following problem may exist. In order to carry about the cutting device after the cutting operation, the cutting unit may be moved to the lowermost position and locked at this position. In such a case, the path from inside of the dust container to the dust discharge member may be inclined downward. Therefore, if the cutting device locked as described above is carried about, the cutting chips may drop from the dust discharge member onto the table by the gravity force. When this occurs, the work environment may be degraded and the cutting operation may be obstructed.
Therefore, there is a need in the art for a cutting device having a further improved dust guide device.